Alduino's brother, Salvatore Alduino, 30, the store's owner, died of injuries from the fire two weeks later. A co-owner, Giorgio Alaimo, of Norridge, said he was just outside the building when the explosion occurred and suffered only minor injuries.

"It was a difficult decision," DuPage County Judge Ronald Mehling said of the acquittal. The judge explained that while it seemed apparent that Alduino participated in the arson, the state didn't prove Alduino's guilt beyond a reasonable doubt.

"The fact that he's in the building, he's employed there and a fire occurs is not enough," Mehling said.

Alduino was expected to be transferred after Wednesday's hearing to Cook County, where he faces drug charges, authorities said.

The state's case against Alduino was largely circumstantial and was based on the theory that the Alduinos tried to set the business ablaze to collect insurance money. A month before the blaze, the company's insurance was boosted to $750,000 from $500,000, authorities said.

A witness reported that in the hour before the fire, she saw the Alduinos shuttling back and forth between several cars and the tile shop, presumably carrying gasoline, authorities said.

But the arson attempt was apparently botched, resulting in the explosion of an internal natural gas line while the brothers were still inside, authorities said.

Witnesses driving along Irving Park Road testified that they heard a boom. The front door of the store flew across Irving Park Road, and the Alduinos, scorched and sooty, ran from the burning building.

"The roof raised off the building and the walls fell in like matchsticks," DuPage County Assistant State's Atty. Robert Spence said in closing arguments.

Spence argued that Giovanni Alduino's hands were burned because they were "wet with gasoline" when the explosion occurred. In the ambulance, Alduino reportedly told paramedics, `I tried to light the oven, and it went, `Boom!' " Spence told the court.

The prosecution's case relied heavily on the testimony of Catherine Loukopoulos, a former girlfriend of Alduino's.

She told the court that Alduino was a silent partner in the business. In the weeks before the fire, Loukopoulos testified, Alduino told her about plans to raise the insurance on the tile company and then set in on fire with gasoline.

But Alduino's attorney, Joe Bugos, characterized Loukopoulos' testimony as sour grapes from a jilted lover. Bugos pointed out that Loukopoulos never testified that Alduino set the fire, and he also questioned why Loukopoulos waited to contact police until after she and Alduino split up.

Bugos also reminded the judge that Loukopoulos composed a three-page letter saying her allegations against Alduino were false. Loukopoulos, who later claimed she composed the letter because Alduino threatened her, wrote that she was "hurt and crazy" by their breakup and wanted Alduino to suffer for his "betrayal."

"She's a vindictive person," Bugos said. "She's unbelievable."

Bugos also told the court that Alduino was simply an employee at the store, not an owner, and would therefore not have a motive to set the blaze.

In explaining his ruling, Mehling noted problems with Loukopoulos' testimony, saying she was "substantially impeached" by her reported recantation and other statements.